Messages in this thread | | | Date | Fri, 23 Sep 2011 09:18:49 +0900 | From | mhban <> | Subject | Re: [PATCH] ARM: futex: fix clobbering oldval |
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On Thu, 2011-09-22 at 18:26 +0100, Will Deacon wrote: > Hi, > > On Thu, Sep 22, 2011 at 03:53:35AM +0100, mhban wrote: > > This patch fixes clobbering oldval bug. oldval should be preserved for next > > compare operation. > > > > Change-Id: I2a63bc1bdb8de330eb9e1ac02d7da1f77e6e8c3c > > Signed-off-by: Minho Ban <mhban@samsung.com> > > It would have been nice to have been CC'd on this...
Will not miss next time. Thanks.
> > I ran LTP tests on this, so I'm surprised that this was broken (the tests > passed). Well spotted anyway! > > > --- > > arch/arm/include/asm/futex.h | 6 +++--- > > 1 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h > > index d2d733c..b0f2e8e 100644 > > --- a/arch/arm/include/asm/futex.h > > +++ b/arch/arm/include/asm/futex.h > > @@ -30,14 +30,14 @@ > > __asm__ __volatile__( \ > > "1: ldrex %1, [%2]\n" \ > > " " insn "\n" \ > > - "2: strex %1, %0, [%2]\n" \ > > - " teq %1, #0\n" \ > > + "2: strex r5, %0, [%2]\n" \ > > + " teq r5, #0\n" \ > > " bne 1b\n" \ > > " mov %0, #0\n" \ > > __futex_atomic_ex_table("%4") \ > > : "=&r" (ret), "=&r" (oldval) \ > > : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \ > > - : "cc", "memory") > > + : "r5", "cc", "memory") > > You shouldn't reference r5 directly here, but due to the way the futex code > is laid out, you can't add an extra output operand without converting the > code to use named arguments. > > I'll post a patch to do that. > > Will
I'm not familiar with gcc inline, thanks for pointing it out.
BTW, my last name is Ban not Ben.
Minho
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